Enhancing plant phosphorus use efficiency for sustainable cropping.

Phosphorus (P) is one of the least available mineral nutrients to the plants in many cropping environments. Sub-optimal P nutrition can lead to yield losses in the range of 10% to 15% of the maximal yields. P deficiency is more critical in highly withered soils as well as in calcareous and alkaline soils. Amelioration attempts by addition of phosphatic fertilizers are economically and ecologically unsound as the efficiency of added phosphatic fertilizers is very low. Inoculation with the mineral phosphate solubilizing microbes has not helped much due to inconsistent performance of the inoculants under field conditions. These factors have led to examine the opportunities for developing genetically enhanced plants with better P use efficiency (PUE) through efficient P absorption, transportation and internal utilization. In order to improve the PUE in crop plants, it is important to explore genetic variation for all its associated traits. Inter- and intra-specific variations for these traits are known to exist and are shown to be under genetic and physiological controls, but modified by the plant-environment interactions. A more comprehensive understanding of the molecular and physiological basis of P uptake, transportation and utilization is leading to formulation of strategies aimed at developing better P efficient cultivars suited for sustainable cropping with less P fertilizer inputs. Issues relating to enhancing PUE through genetic manipulations of crop cultivar parameters are discussed.